US1760568A

US1760568A - Die head

Info

Publication number: US1760568A
Application number: US67136A
Authority: US
Inventors: Harry T Shearer
Original assignee: Landis Machine Co
Current assignee: Landis Machine Co
Priority date: 1925-11-05
Filing date: 1925-11-05
Publication date: 1930-05-27
Anticipated expiration: 1947-05-27

Description

May 27, 1930. H; T. SHEARER DIE HEAD Fild Nov. 5, 1925 '7 Sheets-Sheet DIE HEAD '7 Sheets-Sheet 2 Harry Tshearer H. T. SHEARER Filed Nov. 5, 1925 May 27, 1930;

M EH m 4 mm w Z3 May 27, 1930. I L-T; SHEARER.

DIE HEAD Filed Nov. 5, 1925 7 Sheets-Sheet 3 QH'UWH Har y TS/zearer May 27, 1930.- H. T. SHEARER DIE HEAD Filed Nov. 5, 1925 7 Sheets-Sheet 4 'gwuemtov Harry T511987?! H. T. SHEARER May 27', 1930.

DYIE HEAD Filed Nov. 5. 1925 '7 Sheets-Sheet 5 Zlwuawtoz Harm Tshearer H. T. SHEARER DIE HEAD Filed Nov. 5, 1925 '7 Sheets-Sheet 6 gvvuwntoz Harry T s/768F491" May 27:, 1930; H. T. SHEARER DIE HEAD- I Filed Nov. 5. 1925 '7 Sheets-Shee t 7 grwcwtoz I Evrry TS/veamr Patented May 27, 1930 UNITED .STATES PATENT OFFICE HARRY '1. SI-IEARER, OF WAYNESBORO, PENNSYLVANIA, ASSIGNOR TO LANDIS MA- CHINE COMPANY, OF WAYNESBORO, PENNSYLVANIA, A CORPORATION OF PENNSYL VANIA.

DIE HEAD Application filed November My said invention relates to a die head for machines such as are used for cutting thread on bolts, pipes, etc., and as here shown is embodied in a non-rotary thread-cutting 5 device of the type known'as the Landmatic die head. In the use of heads of this type the head ordinarily travels toward the work but is non-rotary while the work rotates and the opening of the head is usually effected by 1 retardingthe axial movement of the member carrying the head. The improved head here disclosed has distinct advantages over those previously known in economy of manufacture, economical operation of the head and improved character of output. It is to be understood that the application of the various features of the invention, however, is not limited to the specific type of machine shown in the drawings as some of the features may be applied to the head, etc.

The primary object of my invention is to provide a die head of this character in two units divided approximately along a plane perpendicular to the axis of the head. Such 5 a construction affords very important advantages over previously known devices. One advantage resides in the fact that it fa cilitates assembling and disassembling parts of the head which in ordinary constructions are operations of very considerable difficulty and which ordinarily are decidedly timeconsuming.

Another advantage resides in the possibility of accurate adjustment of the endwise float of the trunnions on which the chaser holders are mounted. These chaser holders and trunnions oscillate and therefore a certain amount of clearance is necessary between the end faces of said parts and the parts abutting against them, this making for a certain very limited endwise movement or float between the relatively oscillatory parts which compensates for certain slight inaccuracies occurring in devices of this character. It is essential to the best operation of a thread cutting die head that this float be very limited in extent and precisely the same in different trunnions located in spaced relation about the opening in the head so as to form the threads accurately and precisely 5, 1925. Serial No. 67,136.

on the work and-my invention provides convenient positive and accurate means for securing this result. It is vital also in order to secure good work thatabsolut'e parallelism shall exist between the contacting end faces of the head body, the rings surrounding it and the rear faces of the chaser holders. The two unit head here described makes this more easy to secure and maintain than with the usual constructions heretofore known.

Another object of the invention is the elimination of screws, screw-slots and other features providing dirt pockets on the face of the head, such as are detrimental to successful and economical operation of the same.

Another object is to provide spring means for opening the head which means does not act directly on the chaser holders and so does not affect the float of the chaser holders.

Another object is to provide improved means for rotatably adjusting the head body relativelyto the other parts of the head to vary the size of the opening between the chasers when the head is closed.

Another object of my invention is to provide an improved tripping or head opening mechanism for use in a head having locking pins with blunt ends which are completely withdrawn from the closing ring to permit.

the head to open.

Referring to the accompanying drawings which are made a part hereof and on which similar reference characters indicate similar parts,

Figure 1 is a side elevation of my improved die head with one chaser holder in position thereon,

Figure 2, a face view of the head with three chaser holders removed,

Figure 3, a longitudinal section of the front unit of the head,

Figure 4, a rear view of the front unit, Figure 2 serving as a faceview thereof,

Figure 5, a section on line 55 of Figure 2, Figure 6, a section on line 6-6 of Figure 1, Figure 7, a detail of a part shown in F igure 6,

Figure 8, a section ofthe rear unit of the head, this view being so positioned with reference to Figure 3 as to indicate the position of said units when about to be assembled,

Figure 9, a face View of the rear unit of the head,

Figure 10, a longitudinal section of the as sembled head with the parts in closed position,

Figure 11, a detail section showing the relative positions of certain parts when the head is open,

Figure 12, a front elevation of said parts, partly in section,

Figure 13, an elevation of a locking pin, such as is illustrated in Figures 8, 11 and 12,

Figure, 14, a fragmentary section of a closing ring locked in the closed position of the head by pins of the type shown in Figure 13,

Figure 15, an elevation of a modified locking pin,

Figure 16, a face view of a closing ring locked in the closed position of the head by pins of the type shown in Figure 15,

Figure 17, an elevation of a modified lockmg pin,

Figures 18 and 19, fragmentary cross sections of a closing ring locked in different operative positions by a pin such as shown in Figure 17,

Figure 20, a face view of a front unit employing a closing ring of modified character,

Figure 21, a fragmentary elevation, partly in section, of the device of Fig. 20,

Figure 22, a section on line 22-22 of Fig. 21,

Figure 23, a longitudinal section of a head of the character above referred to, equipped with internal tripping mechanism,

Figure 24, a face view of an internal tripping element,

Figure 25, a face view of a modified chaser holder,

Figure 26, a bottom plan of Figure 25,

Figure 27, a longitudinal section of the chaser holder as shown in Figures 1 and 2 excepting that in Figure 27 the trunnion is integral with the chaser-holder,

Figure 28, an end view of the clamp of the chaser holder as shown in Figures 1, 2 and 27,

Figure 29, a fragmentary end elevation of a chaser holder as shown in Figures 25 and 26,

Figure 30, an end View of the chaser used in the chaser-holder in Figs. 25, 26 and 29,

Figure 31, an end view of the chaser shown in Figures 1, 2 and 27, and

Figure 32, an end view of the clamp used in Figures 25, 26 and 29.

The head comprises a front unit and a rear unit which are readily separable from each other, but in operation are held together by means hereinafter described.

dicates the head body member, which is carried by the assembled front unit. A ring 31 encircles the head body, forward movement of the ring being prevented by an encircling flange 32 engaging in an annular groove in the ring. Behind the ring 31 there is an adjusting ring 33 and beyond this a zero plate 34 having a rearwardly projecting flange 35 bearing zero marks (Fig. 1). The plate is necessarily formed as a ring and has a rela tively small central opening surrounding a reduced rearward extension 36 on the head body. The plate is secured to the head body by means of screws 37. .A pin 38 serves to position the ring relatively to the head body and-for this purpose a series of four holes is provided for engagement by said pin which holes are spaced 90 from each other.

The head body has a longitudinal central opening and a number of bearings parallel thereto in which are journalcd trunnions 39. At their rear ends these trunnions have reduced threaded extensions passing through openings in the ring 34. Nuts 40 threaded on said extensions have flanges 41 bearing against the ring 34. Locking screws 42 (Fig. '10) have threaded engagement in the nuts 40 and are tapered at their forward ends for engagement with tapered recesses in the ends of the trunnions 39. The nuts 40 may readily be adjusted to provide the necessary float for trunnions 39 between flanges 41 of nuts 40, the ring 34, the faces of holders 43 and the faces of ring 31 and head body 30. After the adjustment is made the locking screw 42 is caused to engage the end of the trunnion with sufficient friction to guard against accidental release. It will be seen that the construction of the head with parallel bores and flat end faces makes a very simple job of machining since the bores can be machined straight through so that only straight bores and flat faces need be machined. It is thus a comparatively simple matter to form the contacting faces of the rings, the head, the trunnions and their adjusting nuts very accurately parallel so as to make the parts work easily and reduce to a minimum the error arising from non-parallel parts. By this construction the float of the trunnions may be Very readily and accurately adjusted, with uniform float, all of which is essential for precision work. The machining of the outer and rear faces of the encircling flange 32 so that it will fit in the groove of the closing ring 31 also becomes a relatively simple matter. No depressions are required for screws, nor will there be any projecting screw-heads to interfere with the movement of the chaser-holders, and the possibility of cracks or openings in the face of the head wide enough to admit dirt is reduced to a minimum.

At the forward ends of the trunnions there are chaser-holders 43 fixed to the trunnions for oscillation therewith. The chaser holders are connected to the closing ring 31 by means of pivot pins 44 carrying blocks 45 slidably mounted in slots in the chaser holders. In the present embodiment of the invention the chaserholders are attached to the trunnion by means of screws 46 though in some instances they are made integral therewith.

The rin 33 is provided with one or more openings tting closely about pins 47 on the rear unit. These pins engage at their forward ends in openings in the closing ring thus holding the chasers in operative position for acting on the work. These openings are provided with hardened bushings 48. The purpose of the bushings is to prevent the holes from wearing large at the-entrance which would interfere with quick and accurate entry of the pins 47. It will be seen that when the closing ring moves to bring the bushings out of registry with the pins the pins will bear against the ends of the bushings as clearly shown in Figure 12. Ring 34 is provided with clearance openings (Fig. 4) for pins 47 and for screws 49 by means of which the. front and rear units are held together. I

A pin 50 is fixed in the ring 31, this ring being flattened at opposite sides to provide abutments against either of which a spring 51 may bear. The spring 51'is positioned in a passage in the ring 33 said passage being nearly tangential to the head body and intersecting a chamber at 52 which is open at one side for entry of the pin 50. The spring is held in place by a cap 53 having a hollow end in which the spring is seated. The cap has threaded engagement with such passa e and its movement is limited by a shoulder engagin a shoulder on the ring 33. The other end 0 the passage is closed by a threaded plug 54 having a head resting on another shoulder on the ring 33. Assuming the parts to be in position for cutting a righthand thread it will be seen that when the locking pins 47 are withdrawn the closing ring will be released and the spring 51 will force it in a direction to render the chasers inoperative. A handle 55 on the closing ring serves for returning the ring against action of the spring. If left-hand cutting is to be done the sprmg and the cap 53 are positioned at the opposite side of the abutment 50 and the plug 54 is moved to the lower position in Figure 5.

The spring 51 acts directly in a circumferential direction instead of on the chaserholders as in some prior constructions. lln such rior constructions the springs act on the c aser-holders and their action results in some of the chaser-holders having trunnion play and others not. In actual practice this is of course very detrimental to successful operation of the head, particularly in do-' In addition to themeans for rendering the chasers operative and inoperative, as just described, the front unit of the head is provided with means whereby the diameter of the opening between the cutting edges of the chasers can be varied thus changing the size of the work that can be threaded. Such means comprises a series of worm teeth at 56 on the exterior of the head body engaged by a worm 57 on a bolt or shaft 58 journaled in the ring 33. The bolt is provided at one end with a head 59 underneath which is a flange 60 having graduations shown in Figure 1 coacting with zero marks on the ring 33 to indicate the extent of adjustment. The zero marks on the ring 34 coact with indications on the rear unit of the head to indicate the diameter of the opening between th chasers for either right or left hand cutting. For adjusting the head the bolt 58 is turned, and this rotates the head body and the plate 34 by means of the worm gearing. The

rings

31 and 33 are held against rotation by pins 47 on the stationary shank 63 and the relative rotation of the parts referred to changes the size of the opening between the working edges of the chasers. The extent of relative rotation of ring 34 and the shank is indicated by the scale shown in Figure 1. It will be noted that both sets of indications are visible to a workman who is adjusting the head and this with the self-locking adjustment feature makes adjustment quick and easy. At its lower end the bolt 58 is provided with a thread for a nut 61 and above this is a squared portion receiving a washer 62.

The nut serves to force the washer along the squared portion so as to bring the adjacent faces of the washer andthe flange 60 into frictional engagement with corresponding faces on the ring and so make a neat turning fit. As will be seen in Figure 6 the squared portion of the bolt extends up be yond the face against which the washer 62 rests. When looseness occurs due to wear the washer is forced further along the bolt by turning the nut so as to maintain the fit without backlash, the nut locking itself against the washer. with any special locking arrangement for the worm as the worm is under friction at all times and will not move from its correct setting. Tn certain previous constructions where similar worm gearing was used, the worm being formed as a thread on a bolt extending into a socket in the adjusting ring, the screw so formed had to be forced down into This arrangement does away frictional locking engagement with"the bottom of the socket by means of a locking follower in the shape of a screw plug having threaded engagement with the, upper end of the socket. When the workman after adj usting the head attempted to lock it in adjusted position by means of said clamping screw the worm would sometimes turn and thus spoil the adjustment. This is impossible with the present arrangement and the adjustment of the head is therefore made with great ease and certainty.

The rear unit The assembled rear unit comprises a hollow shank 63 having at its forward end a radial flange 64 with openings 65 in its front face to accommodate the parts 40, 41 and 42 on the front unit. The rear unit has fixed thereto pins 47 projecting forward and serving to lock the closing ring at one end of its stroke with the chasers in operative position. The flange also has recesses to receive screws 49 for engagement with threaded openings in the adjusting ring of the front unit to hold the two units together. Springs 66 are located in said recesses and bear at one end against the bottom of a recess and at the other end against the under side of the head of a'screw 49. The bore of the rear unit is enlarged at 67 to receive the extension 36 on the head body which extension holds the units in line and strengthens the head against lateral strains.

0 pemtz'on In the operation of the device so far described, either right-hand or left-hand chaser holders are mounted on the trunnions and secured thereto by screws 46. The operator brings the chasers into operative position by graspin the handle 55 and turning the ring 31 thus bringing the bores of the bushings 48 into register with the locking pins 47 whereupon the springs 66 move the front unit back, the shank of the rear unit being held securely by a chuck or the like. The work is now brought up into engagement with the chasers and the threading operation proceeds, it being understood that the head advances but does not rotate, while the work does not travel but does rotate though this may be changed in some instances. When the threading of the work has proceeded sufficiently far the axial traveling movement of the rear unit of the head is stopped by some convenient means and thereupon further relative rotation of the parts draws the front unit forward away from the rear unit against the tension of spring 66 until the pins 47 withdraw from the bushings 48 whereupon the ring 81 is moved by its spring 51 in a direction to move the chasers toward inoperative position, the pressure of the spring 51 being reenforced by the reaction of the work against the chasers which, of course, tends to open the head.

Modifications In Figures 15 and 16 I have shown a modified form of the pin 68 having a reduced end at 69. This pin may be used in a head substantially similar to that above described, the closing ring 31-being provided with bushings 48 as before, if desired. When the chasers are in operative position the body of the pin enters the bushings but when the chasers are operative the parts assume the position shown in Figure 16. It may be remarked that the front and rear units have relative axial movement in one way or the other to release the pins from the closing ring and permit the head to open, i. e. the chasers to become inoperative.

In the modified form shown in Figures 17 to 19 pins 7 O are shown each of which has a handle 71 by which it may be turned about its axis through an arc of 180. The pins are each provided with a collar 72 which rests in a depression in the front face of the flange 64 of the rear unit. The pins are each provided with an eccentric end portion formed by reducing the body of the pin at one side for a short distance back from its end face.

The operation of the device with the modified pins is similar to that first described but this form permits the making of either a single cut or of a rough out followed by a finishing cut. Assuming that the parts are shown in the position for a rough cut the chasers will operate as first described. For a second or finishing cut the handles 71 will be turned, e. g. from the position shown in Fig. 18 to that shown in Fig. 19 and the cutting operation will be repeated whereupon a small amount of metal will be removed producing a smoother result than with a single out. The eccentric face 73 of the pin is formed on the arc of a circle corresponding to the circle of the hole in the bushing with which the face is to engage. In this manner the face of the pin is caused'to fit against the inner face of the bushing without line contact. When the direction of cutting is to be reversed the rough and finishing cuts may be had by merely reversing the positions of the handles 71.

The modification shown in Figs. 20 to 22 is similar to that first described. The closing ring 31', however, is provided with a pair of recesses 74 separated by a face at 75 of reduced height relatively to the rear face of the ring 31. The bushings 48 have reduced portions to correspond to this face. This form of the invention is desirable where the handle 55 of the closing ring is moved toward closing position by a cam in that it permits overtravel of the ring 31' and so causes the pins 47 to take a position in the shallow intermediate part of the recesses. When the handle 55 now is released by the cam the ring 31 is moved back by spring 51 and pins 47 assume their positions in the bores of the bushings 48. In the absence of an overtravel arrangement the positive action of the cam might result in injury to some of the parts. In-the modification shown a closing cam can be set without close relation to the closed position of ring 31'.

In the form of the invention shown in Figare 23 the head which may otherwise be similar to that of Fig. 1 is provided with an internal trip coacting with the work 76 for movingthe front unit axially with reference to the rear unit to release pins 47 from the bushings 48 in the ring 31 and thus permit the closing ring to rotate and move the chasers into inoperative position, the trip mechanism comprising a head 77 having recesses 78 for clearance for .chasers when cutting short threads and a circular flange 79 at the rear end fitting in the bore of the head body 30. A stem 80 extends rear'wardly into the bore of the shank 63. The bore is threaded at its rear end to receive a screw plug 81 by means of which the position of the head 77 may be varied to vary the length of the thread formed on the work 76.

Uhasers and chaser holders Figures 27, 28 and 31 show details of the chaser and chaser holder used in this die head. In the chaser holder shown in Figure 27 the trunnion 82 is made integral with the body 43 of the holder. In the forms partially shown in Figures 10 and 23 the trunnion is detachably secured to the body of the holder. The holder is provided with a recess formed by the intersection of an inclined face 100 and a back surface 101, in which recess a chaser 83 is mounted and held in position by means of a clamp 86. The clamp has longitudinal fins 87 and 90, the former inclinedat an angle about'60 to correspond to an undercut face 99 at the back of the chaser. The intersection of the planes of the faces 87 and 88 is rounded off to correspond with a groove at the bottom of

faces

89 and 99 on the chaser 83. When in position the face 88 on the clamp is spaced a short distance from the face 89 on the chaser. The face 90 is inclined at an angle about 45 and the ridge of the clamp is squared at 91, the ridge also having another inclined edge at 92. The chaser holder has a groove formed at the intersection of faces 102 and 95, the groove being squared at the bottom to provide a space between the edge of the fin and the block to take care of dirt which might otherwise accumulate between the face 90 on the clamp and the face 102 on the holder. A face 94 on the clamp is arranged to lie flat against face 95 on the holder. The clamp is held to the block by means of screws 96 and the chaser may be adjusted longitudinally of the holder by means of a screw plug 97. Although the chaser 83 is somewhat similar to chasers heretofore used it differs from them in that the

surfaces

85 and 98 alone are accurately finished. The clearance between the face 89 on the chaser and the face 85 on the clamp allows for inaccuracies in the other surfaces of the chaser, and the clamp.

In Figures 25, 26, 29 and 30 are shown modifications of the chaser and chaser holder shown in Figures 2 and 27. The chaser 83 has facesl05 and 108 which correspond to

faces

85 and 98 on the chaser 83 but the face 106 extends over the entire thickness of the chaser instead of being formed in two parts 99 and 107, as in Figure 31. 'The back 108 extends in a single plane over the entire width of the chaser instead of being in two

parallel planes

98 and 89, as in Figure 31. This chaser can be finished much more readily than that shown in Figure 31. The clamp 86, shown in Figures 29 and 32 has a face 104 which extends out over the top 106 of the I chaser. A rib 103 extends in acorresponding groove in the holder block. In this form the face 103 is inclined at approximately 45 and face 104: at approximately 75.

In further explanation it may be stated that the position of the nuts 40 makes it very easy to adjust the trunnions when the front and rear units are separated, as Well as to ass mble the front unit or take it apart. In previous construction the nuts or adjusting screws for holding the trunnions and determining their fioat were inside the bores of 'the head body; i. e. forward of the rear face of said body and hard to get at. Even when flush with said face they were more difiicult to manipulate than in the present device.

The use of a single axial locking screw on the trunnion does away with any tendency to tilt the adjusting nut in looking the adjusting nut in place. In some previous constructions, where three or more locking screws were used unequal tightening of the locking screws tended to cause misalinement of the adjusting screws.

By means of the new construction I avoid the use of a separate front holding ring on the head body. It is a matter of great difficulty to machine the front and rear faces of a separate rin such as that shown at 30 in the patent to llIiller 1,296,546 so accurate-1y that the rear face will lie closely against the faces in the annular depressions on ring 15 and head body A (which surfaces must also be machined accurately) while the front face of the ring lies in the plane of the front faces of ring 15 and head body A. In practice the expense of such exact machining is prohibitive, and the recess in the head body is cut deeper than necessary, after which annular shims are used to fill the space between the holding ring and the head body, when it frequently happens that the holding ring is caused to project forward too far.

The inner and outer peripheral surfaces of the holding ring must also be machined accurately so as not to leave cracks in which dirt may accumulate whereby also the smoothness of the front face of the head may be impaired as by reason of metal chips catching in such cracks. Such chips also often catch in the slots of the exposed screw-heads and interfere with the opening and closing of the head. The holding ring has depressed seats for the screws which seats often break down more or less and render the holding action uncertain. Also the screw-heads often become bent and interfere with the headopening and closing movements. These difficulties are avoided in my present device where the front holding ring is integral with the head body and the shims, if any, are positioned between the head body and the rear ring of the front unit of the head body and can be of substantial width instead of being of no greater width than the holding ring of the prior construction, thus being made more permanent and more effective. The prior construction in which the rear holding ring of the head body is integral and the front holding ring is removable made a die head which was very difficult to take apart, it being practically impossible to pry the ring out or otherwise remove it from its seat with tools. With the present construction the units can readily be separated. Plate 34 of the front unit can readily be removed-by taking out screws 37, removing nuts 40, and taking out bolt 58. The entire front unit will then come apart.

The two unit head is a matter of convenience also in the factory in that the front unit can be used Without alteration with either a plain rear unit or with a rear unit including a trip mechanism as shown in Figure 23. The same details can also be used with a head of the Lanco type as shown in my copending application No. 59,563, filed September 30, 1925. This makes it possible to fill orders for either plain heads or heads with trips with a smaller number of actual parts held in the stockroom.

Another feature of advantage in the present construction resides in the fact that the bores for the trunnions pass straight through the head body. In prior constructions they commonly are counterbored either from one or both ends of the head body and the bores must be finished from one or both ends, this necessitating a much greater number of operations than in the present construction and giving a less accurate result as compared with the resent construction where all the finishing is either on the walls of the straight bores or on the flat outer contacting faces at the rear of the head body and at the front of th rear plate 34.

By my present construction the scale on the periphery of the head is in plain view while the bolt 58 is being operated to adjust the head, as is also the scale on flange 60, which conduces to quick adjustment.

It sometimes happens after a head has been in use for several years that the gear teeth 56 on a segment of the head body become worn so that there is some backlash between the body 30 and the worm 57 In such cases it is of advantage to separate the front and rear units, remove the screws 37 and plate 34, adjusting the head body around and then replace plate 34.- to bring one of the other holes in register with the pin 38. Then the ring 34 has now again been secured to the front unit the zero marks are brought into the same position as before relative to the graduations on the flange 64, and a new set of teeth takes the wear in adjusting the head.

It will be obvious to those skilled in the art that various changes may be made in my device without departing from the spirit of the invention and therefore I do not limit myself to what is shown in the drawings and described in the specification but only as indicated in the appended claims.

Having thus fully described my said invention, what I claim as new and desire to secure by Letters Patent, is:

1. In a die head, a'front unit including a body having longitudinal cylindrical bores of uniform diameter, trunnions in said bores said trunnions having reduced rearward extensions, a plate at the rear of the unit having openings for said extensions, means for holding the trunnions in place relatively to said plate, and chaser-holders on the front ends of said trunnions, substantially as set forth.

2. In a die head, a front unit including a body having longitudinal cylindrical bores of uniform diameter, trunnions in said bores said trunnions having reduced rearward extensions, a plate at the rear of the unit having openings for said extensions, means for holding the trunnions in place relatively to said plate, chaser-holders on the front ends of said trunnions, a separate rear unit having recesses in line with said trunnions, and resilient means holding said units together, substantially as set forth.

3. In a die head, an assembled front unit having a head body with parallel bores of uniform diameter, an integral annular flange at its forward end, a closing ring and an ad justing ring on said body, a plate at the rear end of the body, chaser-supporting trunnions in said bores held in place by said plate, an assembled rear unit resiliently held in engagement with the front unit, and pins fixed to said rear unit slidably mounted in the adjusting ring said pins engaging the closing ring to lock it in one position, substantially as set forth.

4. In a two-unit die head, an assembled .extension, trunnions in bores in the head body bearing at their rear ends against said rearmost ring, threaded extensions on the trunnlons projecting through holes in said ring, nuts on said extensions bearing against the rear face of said ring, and tangential 139 chasers supported on said trunnions, substantially as set forth.

5. In a two-unit die head, an assembled front unit comprising a head body, rings about said body, a rearward extension on said unit the real-most ring fitting about said extension, trunnions in bores in the head body bearing at their rear ends against said rearmost ring, threaded extensions on the trunnions projecting through holes in said ring, nuts on said extensions bearing against the rear face of said ring, tangential chaserholders on said trunnions, and locking screwplugs in said nuts bearing against the rear ends of said extensions, substantially as set forth. l

6. In a two-unit die head, an assembled front unit comprising a head body, rings about said body, a rearward extension on said unit the rearmost ring fitting about said extension, trunnions in bores in the head body hearing at their rear ends against said rearmost ring, threaded extensions on the trunnions projecting through holes in said ring, nuts on said extensions bearing against the rear face of said ring, tangential chaserholders on said trunnions, and locking screwplugs in said nuts having tapered front ends engaging in tapered holes in said threaded extensions, substantially as set forth.

7. In a die head, a front unit comprising a head body having trunnion bearings, trunnions in said bearings, chaser-holders on said trunnions, tangential chasers on said holders, a closing ring about the body connected to said chaser-holders, an adjusting ring about the body, a ring about a reduced extension of said body, means for securing said ring to said body, means for securing the trunnions to the last-named ring to prevent axial movement of the trunnions, a separate rear unit, pins on the rear unit slidably mounted in said adjusting ring and adapted to engage recesses in said closing rin and means for holding said units yieldafily in contact with each other, substantially as set forth.

8. In a die head, a front unit comprising a body member having parallel axial bores therethrough, trunnions mounted in said bores, chaser holders mounted on the trunnions, tangential chasers in the holders, a closing ring'mounted on said body and connected to said chaser holders, an adjusting ring mounted on said body, means for adjusting said rings around said body to vary the cutting size of said die head, a peripheral flange at the front of said body and a circular plate secured to the rear of said body for holding said rings in axial position on the body, said plate being connected to and securing the trunnions against axial movement of said body, and a separate rear unit having means thereon for locking the said closing ring in operative position, substantially as set forth,

9. In a die head, a front unit comprising a body member having parallel bores therethrough, trunnions mounted in the bores,

chaser holders mounted on the trunnions,

rear of said member by which the rings are held against axial movement relative to the said body, the said plate being connected .to and positioning said trunnions against axial movement in said body, and a separate rear unit including a shank, pins fixed thereon extending through said plate and the said adj usting ring of the front unit and adapted to engage sockets in the closing ring for locking said ring in operative position, substantially as set forth.

, 10. In a die head, a front'unit comprising a head body having parallel axial bores therethrough, trunnions mounted in the bores, chaser holders mounted on the trunnions, tangential chasers in the holders, a closing ring mounted on said body and connected to said chaser holders, an adjusting ring mounted on said body, said rings being held against axial movement on said body by a peripheral flange on the front of the body and a circular plate secured to the rear of the holding the trunnions against axial movement of said body, a separate rear unit comprising a shank, pins fixed thereon extending through the said plate and through the adjusting ring of the front unit and adapted to engage bores in the closing ring on the front unit for locking the head in operative position, said front unit and said rear unit having relative axial movement for releasing said locking means, and resilient means for opposing such movement, substantially as set forth. I

11. In a die head, a front unit comprising a body member having parallel axial bores therethrough, trunnions mounted "in the bores, chaser holders mounted on the trunnions, tangential chasers in the holders, a closing ring mounted on said body connected to the chaser holders, an adjusting ring mounted on said body, said rings being held against axial movement relative to said body by a periphe'ralflange on the front of said body and a plate secured to the rear of said body, the. said plate also being connected to and securing the trunnions against axial: movement in said body, a separate rear unit including a shank, pins fixed thereon adapted to extend through the said plate and the said adjusting ring on the front unit into bores in a closing ring on the front unit for looking said die head in operative position, and means on the rear unit for locking the chasers in operative position for either a roughing cut or a finishing cut, substantially as set forth.

12. In a die head, a removable front unitcomprising a body, rings encircling said body, tangential chasers mounted in holders,

m holders mounted on trunnions, the body having parallel axial bores of uniform diameter throughout, trunnions mounted in the bores in said body, said trunnions extending throughout the length of said body and having reduced portions extending through a plate on the rear of the body, and having nuts on the reduced portions by means of which the trunnions are held against axial movement substantially as set forth.

13. In a die head, an assembled front unit comprising a body member, rings encircling said body, a ring or plate at the rear of said body cooperating With a peripheral flange at the front of said body to hold said rings 5 against axial movement, bores of uniform diameter extending throughout the length of said body, trunnions mounted in said bores and extending throughout the length of said body, tangential chasers on the trunnions, the

said trunnions having reduced ends extending through the said plate and being held against axial movement in the body by the said plate on the rear of the body, substantially as set forth.

:5 14. In a die head the combination of a front unit comprising a front head body member, chaser-holders pivotally supported thereon, tangential chasers on the holders, a closing ring connected to the chaser-holders,

an adjusting ring, a ring coacting with a flange on the head body for holding the closing and adjusting rings in place, and means for securing the last-named ring to the front head body member, a separate rear unit comprising a rear head body member, means thereon for locking the closing ring in head closin position, and means for securing the head body members together, substantially as set forth.

15. In a die head, a front unit comprising a head body member having an integral annular flange at its forward end, chaserholders', a closing ring surrounding the body member, a ring adjustably secured to the body, a zero platevcoacting with said flange to hold the rings in place, graduations on the periphery of said plate, and means securing the zero plate in place on said body member in a plurality of angularly related positions,

00 substantially as set forth.-

I 16. In a die head, a head body, chaserholders thereon, a ring frame about the body including an adjusting ring, a closing ring, axially movable rings, pins on said axially B5 movable rings for locking the closing ring in head closing position said pins sliding in bearings on said adjusting ring, a Worm journaled on the adjusting ring, Worm-teeth on the body engaged by said Worm, a head on the worm bearing against a face on the ring, a Washer at the other end of the Worm bearing against a face on said ring said Washer having a square opening fitting a square part of said worm, and a nut on a threaded end portion of the worm, substantially as set forth.

In Witness whereof, I have hereunto set my hand at l/Vaynesboro, Pennsylvania, this 31st day of October, A. D. nineteen hundred and twenty-five.

HARRY T. SHEARER.